U.S. patent number 10,959,477 [Application Number 15/307,423] was granted by the patent office on 2021-03-30 for ear muff attachment having dual axis of rotation.
This patent grant is currently assigned to 3M Innovative Properties Company. The grantee listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Emil J. Jonsson, Sigvard Nilsson, Henrik Nordin.
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United States Patent |
10,959,477 |
Nordin , et al. |
March 30, 2021 |
Ear muff attachment having dual axis of rotation
Abstract
The present description provides an ear muff attachment
assembly. An exemplary ear muff attachment assembly (100) includes
a housing (110), an ear muff (130), an arm (120) having first and
second end regions, the first end region positioned within the
housing and the second end region attached to the ear muff, and a
spring (150) engaged to the housing and the first end region of the
arm. The arm is rotatable about a first axis of rotation between a
first position and an intermediate position, and about a second
axis of rotation between the intermediate position and a second
position.
Inventors: |
Nordin; Henrik (Forsheda,
SE), Nilsson; Sigvard (Varnamo, SE),
Jonsson; Emil J. (Malmo, SE) |
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Assignee: |
3M Innovative Properties
Company (St. Paul, MN)
|
Family
ID: |
1000005451534 |
Appl.
No.: |
15/307,423 |
Filed: |
April 23, 2015 |
PCT
Filed: |
April 23, 2015 |
PCT No.: |
PCT/US2015/027296 |
371(c)(1),(2),(4) Date: |
October 28, 2016 |
PCT
Pub. No.: |
WO2015/167924 |
PCT
Pub. Date: |
November 05, 2015 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
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US 20170049179 A1 |
Feb 23, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61987873 |
May 2, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A42B
3/166 (20130101) |
Current International
Class: |
A42B
3/16 (20060101) |
Field of
Search: |
;2/423,6.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2013-101441 |
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Jan 2014 |
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AU |
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3343492 |
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Jun 1984 |
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DE |
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4234216 |
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Dec 1993 |
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DE |
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271078 |
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Aug 1983 |
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ES |
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1456956 |
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Dec 1976 |
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GB |
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2009-024312 |
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Feb 2009 |
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JP |
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2010-018933 |
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Jan 2010 |
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JP |
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WO 1986-03656 |
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Jul 1986 |
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WO |
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Other References
International Search Report for PCT International Application No.
PCT/US2015/027296, dated Jul. 16, 2015, 4 pages. cited by
applicant.
|
Primary Examiner: Hoey; Alissa L
Attorney, Agent or Firm: Scholz; Katherine M. Ehrich; Dena
M. Karlen; Christopher D.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national stage filing under 35 U.S.C. 371 of
PCT/US2015/027296, filed Apr. 23, 2015, which claims the benefit of
Provisional Application No. 61/987,873, filed May 2, 2014, the
disclosure of which is incorporated by reference in its/their
entirety herein.
The present invention pertains to an ear muff attachment mechanism
that rotates about first and second axes between an active position
and a standby position.
Claims
What is claimed is:
1. An ear muff attachment assembly, comprising: a housing with a
protrusion that forms a first lever seat and a second lever seat on
the housing and; an ear muff; an arm comprising a first end region
and a second end region, wherein the first end region comprises a
first lever seat engaging structure, extending from the arm, and a
second lever seat engaging structure, extending from the arm;
wherein the first lever seat engaging structure, when engaging the
first lever seat, forms a first axis of rotation for the arm, and
wherein the second lever seat engaging structure, when engaging the
second lever seat, forms a second axis of rotation for the arm;
wherein the arm is rotatable about the first axis of rotation
between a first position and an intermediate position, and about
the second axis of rotation between the intermediate position and a
second position, and wherein the protrusion interacts with the arm
such that the protrusion is in between the first and second lever
seat engaging structures as the arm moves between the first
position, the intermediate position, and the second position; and
wherein a spring is positioned within the housing and contacts a
spring retention feature of the first end region on a first spring
end and contacts the housing on a second spring end, and wherein
the spring exerts a first spring force between the first position
and the intermediate position that acts to return the arm to the
first position, and a second spring force between the intermediate
position and the second position that acts to return the arm to the
second position, and wherein the spring retention feature comprises
a recess.
2. The ear muff attachment assembly of claim 1, wherein the first
lever seat engaging structure and the second lever seat engaging
structure are positioned on the arm to form a recess on the arm
that receives the protrusion, wherein the protrusion is a shaped
such that it engages the first and second lever seat engaging
structures, respectively, in each of the first and second
positions.
3. The ear muff attachment assembly of claim 1, wherein the first
and second lever seat engaging structures are positioned on the arm
such that a groove is formed, wherein the groove receives the
protrusion.
4. The ear muff attachment assembly of claim 1, wherein the first
and second axes of rotation are parallel.
5. The ear muff attachment assembly of claim 1, wherein the spring
is a spring selected from the group consisting of a coil spring,
leaf spring, and wire spring.
6. The ear muff attachment assembly of claim 1, wherein the ear
muff is in an active position configured to cover a user's ear when
the arm is in the first position and the ear muff is in a standby
position away from a user's ear when the arm is in the second
position.
7. The ear muff attachment assembly of claim 6, wherein the arm
exerts a force (F) at the second end region, and a first maximum
force exerted between the first position and the intermediate
position (Fmax1) is greater than a second maximum force (Fmax2)
exerted between the intermediate position and the second
position.
8. The ear muff attachment assembly of claim 1, wherein the ear
muff is removably attached to the second end of the arm.
9. The ear muff attachment assembly of claim 1, wherein the ear
muff is adjustably attached to the second end of the arm.
10. An ear muff attachment assembly, comprising: a housing
comprising a first lever seat defining a first axis of rotation and
a second lever seat defining a second axis of rotation and a
protrusion between the first and second lever seats; an arm
comprising a first end region and a second end region, the first
end region comprising a first lever seat engaging structure and a
second lever seat engaging structure that are each rotatably
engageable with the first and second lever seats, respectively, and
wherein the first and second lever seat engaging structures are
positioned on the arm on either side of a recess that receives the
protrusion, and wherein the engagement between the first and second
lever seat engaging structures and the first and second lever seats
allow the earmuff attachment assembly to move around the first and
second axes of rotation, wherein the second axis of rotation is
parallel to the first axis of rotation, and the second end region
comprises an ear muff; and a spring within the housing that is
attached to a spring retention feature on the first end region of
the arm within the housing, on a first spring end, and is attached
to the housing on a spring second end, and wherein the spring
retention feature is a recess that receives the spring; wherein the
arm is rotatable about the first axis of rotation between a first
position and an intermediate position, and about the second axis of
rotation between the intermediate position and a second position,
and wherein the spring is rotatably engageable such that it exerts
a first spring force between the first position and the
intermediate position that acts to return the arm to the first
position, and exerts a second spring force between the intermediate
position and the second position that acts to return the arm to the
second position.
11. An ear muff device, comprising: a helmet; and a first earmuff
attachment assembly and a second ear muff attachment assemblies,
each attached to the helmet, each of the first and second ear muff
attachment assemblies comprising: an earmuff housing comprising a
first lever seat defining a first axis of rotation and a second
lever seat defining a second axis of rotation, wherein the first
and second lever seats are positioned, respectively, above and
below a protrusion on the earmuff housing; an arm comprising first
and second end regions, the first end region comprising a first
lever seat engaging structure that rotatably engages the first
lever seat, and a second lever seat engaging structure that
rotatably engages the second lever seat, and wherein the engagement
between the first and second lever seats and the first and second
lever engaging structures causes one of the first or second earmuff
attachment assemblies to rotate about the protrusion on the first
and second axes of rotation, wherein the second axis of rotation is
parallel to the first axis of rotation, and the second end region
comprises an ear muff; and a spring attached to the earmuff housing
on a first spring end and contacts, on a second spring end a recess
in the first end region of the arm within the housing; wherein the
arm is rotatable about the first axis of rotation between a first
and an intermediate position such that the arm rotates about the
protrusion in the first lever seat between the first and
intermediate position, and about the second axis of rotation
between the intermediate position and a second position such that
the arm rotates about the protrusion in the second lever seat
between the intermediate and the second position, and wherein the
spring exerts a first spring force between the first position and
the intermediate position that acts to return the arm to the first
position, and a second spring force between the intermediate
position and the second position that acts to return the arm to the
second position.
12. The ear muff device of claim 11, further comprising an adapter
attachable to the helmet and having a slot configured to slidably
receive a mating feature of the housing.
13. The ear muff device of claim 11, wherein the first position the
ear muff is in an engaged position configured to cover a user's ear
and the second position is a second engaged position configured to
position the ear muff over a user's ear.
Description
BACKGROUND
The use of hearing protective and noise isolating devices are well
known, and various types have been considered. Such devices include
ear muffs that are placed over the ear of a user to physically
obstruct the passage of sound waves into the inner ear. Ear muffs
typically include a cup-shaped shell including a sound absorber or
liner. Ear muffs may be supported on or around the head of a user
by a head band, strap, helmet or other headpiece. Helmets, such as
hard hats, and other head gear may be worn with ear muffs including
an arm that attach to the helmet and may be adjustable between
various positions over or away from a user's ear. Various helmet
mounted ear muffs are available, such as 3M PELTOR X SERIES helmet
mounted ear muffs available from 3M Co. of St. Paul, Minn.
SUMMARY OF THE INVENTION
Prior helmet mounted devices often require the same level of force
to rotate into an active position as required to rotate to a
standby position. Accordingly, range of motion of the ear muff is
often intentionally limited to avoid an excessive force to move the
ear muffs into an active position and to limit a force exerted by a
pre-stressed component of the assembly when in a standby position.
An ear muff attachment assembly according to the present
description may be configured such that a maximum force to move an
ear muff into an active position is different (e.g. less than) a
maximum force to move the ear muff into the standby position.
Desired force levels and range of motion may be provided while
providing an ear muff attachment assembly that is easy to use and
minimizes force of a pre-stressed component when in a standby
position.
The present description provides an ear muff attachment assembly
including a housing, an ear muff, an arm having first and second
end regions, the first end region positioned within the housing and
the second end region attached to the ear muff, and a spring
engaged to the housing and the first end region of the arm. The arm
is rotatable about a first axis of rotation between a first
position and an intermediate position, and about a second axis of
rotation between the intermediate position and a second
position.
The present description further provides an ear muff attachment
assembly including a helmet and first and second ear muff
assemblies attached to the housing. Each of the first and second
ear muff assemblies include a housing having a first lever seat
defining a first axis of rotation, an arm including first and
second end regions, the first end region having a second lever seat
defining a second axis of rotation, and the second end region
including an ear muff, and a spring engaged to the housing and the
first end region of the arm within the housing. The arm is
rotatable about the first axis of rotation between a first position
and an intermediate position, and about the second axis of rotation
between the intermediate position and a second position. The ear
muffs are in an active position when the arm is in the first
position and are in a standby position when the arm is in the
second position.
The above summary of the present invention is not intended to
describe each disclosed embodiment or every implementation of the
present invention. The Figures and the Detailed Description, which
follow, more particularly exemplify illustrative embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
The present description will be further explained with reference to
the appended Figures, wherein like structure is referred to by like
numerals throughout the several views, and wherein:
FIG. 1 is a perspective view of a helmet and exemplary ear muff
attachment assembly 100 according to the present description.
FIG. 2 is an exploded view of a helmet and exemplary ear muff
attachment assembly 100 according to the present description.
FIGS. 3a, 3b, and 3c show a representative schematic view of an
exemplary ear muff attachment assembly 100 in first, intermediate,
and second configurations.
While the above-identified figures set forth various embodiments of
the disclosed subject matter, other embodiments are also
contemplated. In all cases, this description presents the disclosed
subject matter by way of representation and not limitation. It
should be understood that numerous other modifications and
embodiments can be devised by those skilled in the art which fall
within the scope and spirit of the principles of this
description.
DETAILED DESCRIPTION
The present description provides an ear muff attachment assembly
that allows a user to move an ear muff between an active position
and a standby position. The ear muff attachment assembly includes a
housing, an ear muff, and an arm engaged with the housing and the
ear muff. The arm is rotatable about a first axis of rotation
between a first position and an intermediate position, and about a
second axis of rotation between the intermediate position and a
second position. Rotation about first and second axes allows a
force required for rotation into an active position to differ from
a force required for a user to rotate the ear muffs into a standby
position. For example, less force may be required to position the
ear muffs over the user's ear than to position the ear muffs away
from a user's ear. Accordingly, an ear muff attachment assembly as
described herein allows a user to more easily move ear muffs
between an active position and a standby position while reducing
stress on components to maximize usable life of the assembly.
FIGS. 1 and 2 show an exemplary ear muff attachment assembly 100
including a housing 110, an arm 120 and ear muff 130. Arm 120 is
rotatable between a first position and an intermediate position,
and between the intermediate position and a second position, such
that ear muff 130 may be adjusted and/or toggled, for example,
between active and standby positions. In an active position, ear
muff 130 is configured to at least partially cover a user's ear. In
a standby mode, ear muffs 130 are in a raised position away from
and/or out of contact with a user's head. A user is able to switch
between active and standby positions when entering or leaving an
area necessitating hearing protection, for example, or as may be
desired by the user. Adjustment to a standby position allows ear
muffs 130 to be readily available for the user to move ear muffs
130 into an active position in which hearing protection is provided
without the need to carry or store ear muffs.
Housing 110 may be attached directly or indirectly to a helmet,
hard hat, strap, head band, or other head support, such as a helmet
50 shown in FIG. 1, for example. Helmet 50 may be worn
simultaneously with, and provide a support for, ear muff attachment
assembly 100. Housing 110 is attached to an outer surface of helmet
50, and arm 120 extends generally downwardly around an edge of
helmet 50 such that ear muffs 130 may be desirably positioned to
cover a user's ear. A second housing 110 and ear muff assembly 100
is similarly attached to an opposite side of helmet 50.
In an exemplary embodiment, housing 110 is attached to a helmet 50
via an adapter 140. Adapter 140 includes a tab or protrusion 141
received by a complementary feature 51, such as slot, opening,
projection, or other suitable feature, of helmet 50. Adapter 140
and housing 110 include complementary features that interact to
provide a permanent or releasable engagement. For example, housing
110 includes a flange 117 that is slidably received in one or more
slots 142 of adapter 140 and frictionally or mechanically retained.
In various exemplary embodiments, helmet 50, housing 110, and/or
adapter 140 may also be joined using various other suitable
components, such as snap-fit components, rivets, mechanical
fasteners, adhesive, or other suitable attachment components as
known in the art.
Ear muff 130 is configured to cover at least a portion of a user's
ear and/or head. In an exemplary embodiment, ear muff 130 exhibits
a cup shape and includes a cushion 137 and a sound absorber (not
shown). Cushion 137 is configured to contact a user's head and/or
ear when ear muff 130 is in an active position forming an
appropriate seal to prevent sound waves from entering.
Arm 120 extends outwardly from housing 110 and is configured to
carry ear muff 130. Arm 120 includes a first end region 121
proximate housing 110 and a second end region 122 spaced from first
end region 121. In an exemplary embodiment, first end region 121
extends through an opening 112 in housing 110 and is engaged with
spring 150 within housing 110. Second end region 122 of arm 120 is
attached to ear muff 130. In an exemplary embodiment, arm 120 has a
"Y" or branched shape such that second end region 122 of arm 120
includes two or more portions joined to ear muff 130 at attachment
locations 131, 132 on first and second sides of ear muff 130. In
other exemplary embodiments, second end region 122 of arm 120 may
be attached to an attachment location 133 on an outer face 134, or
one or more other locations, of ear muff 130.
In an exemplary embodiment, second end region 122 of arm 120 is
rotatably attached to ear muff 130. A rotatable attachment allows
ear muff 130 to rotate or pivot relative to arm 120 to facilitate a
comfortable fit and robust seal with a user's head and/or ear. In
some exemplary embodiments, arm 120 may have an adjustable length,
for example by frictionally engaged concentric portions 120a and
120b, such that a vertical position of ear muff 130 may be adjusted
to accommodate a range of user head sizes and/or desired
positionings.
Arm and housing may be made of any suitable material that provides
sufficient stiffness and durability such that arm 120 and ear muff
130 may be repeatedly moved between first and second positions. In
an exemplary embodiment, arm 120 is made of an acetal and housing
110 is made of a polyamide, such as a glass fiber reinforced
polyamide.
Ear muff attachment assembly 100 includes a spring 150 that engages
housing 110 and arm 120. In an exemplary embodiment, spring 150 is
formed from a resilient metal wire having a cylindrical
cross-section and flexed into a generally oval or ring shape. A
first spring engagement portion 151 engages housing 110 at a
housing spring retention feature 113. Housing spring retention
feature 113 may include a recess 113a, or other feature
complementary to spring 150, such that spring 150 may be retained
in an engaged position during normal use of ear muff attachment
assembly 100. A second spring engagement portion 152 engages first
end region 121 of arm 120 at an arm spring retention feature 123.
Arm spring retention feature 123 may include a recess 123a, or
other feature complementary to spring 150, such that spring 150 may
be retained in an engaged position during normal use of ear muff
attachment assembly 100. In various exemplary embodiments, spring
150 may include a coil spring, leaf spring, or other suitable
spring as known in the art, and/or may be integral to housing 110
and/or arm 120.
In an exemplary embodiment, spring 150 is rotatably engaged with
arm 120 and housing 110 such that spring 150 is able to rotate
relative to housing 110 and/or arm 120 at first and second spring
engagement portions 151, 152. That is, first and second spring
engagement portions 151, 152 are able to rotate about first and
second spring axes 30, 40, for example.
Spring 150 exerts a spring force (Fs) resulting from compression or
activation of spring 150. In an exemplary embodiment, spring force
(Fs) results from compression of spring 150 from a neutral or
initial spring length (Li) to a spring length (Ls), for example
between first and second engagement locations 151, 152. Compression
or activation of spring 150 results in a spring force (Fs) on first
end region 121 of arm 120 that may act to move arm 120 towards a
first or second position. In some exemplary embodiments, spring
force (Fs) is proportional to compression of spring 150 multiplied
by spring constant (K) and thus varies with spring length (Ls) as
arm 120 moves between first and second positions.
Spring force (Fs), and the geometry and configuration of ear muff
attachment assembly 100, results in a force (F) exerted at second
end regions 122 and ear muffs 130 that varies based on the position
of arm 120. For example, when in an active position, force (F)
pushes ear muff 130 towards a user's ear. Force (F) acts to retain
ear muff 130 in the active position and facilitates a seal between
ear muff 130 and the user's ear and/or head to physically prevent
sound from entering a user's ear. As arm 120 is moved between a
first position and an intermediate position, force (F) acts to
return arm 120 and ear muff 130 to the first position. Similarly,
as arm 120 is moved between a second position and an intermediate
position, force (F) acts to return arm 120 and ear muff 130 to the
second position. In an exemplary embodiment, force (F) is
approximately zero at the intermediate position. That is, in an
exemplary embodiment, force (F) is approximately zero and switches
direction as arm 120 passes to either side of the intermediate
position. Force (F) results primarily from spring 150 and component
configuration and geometry of ear muff attachment assembly 100 and
can be configured to result in a desired force at ear muff 130 as
described herein.
FIGS. 3a through 3c show cross-sectional schematic views of an
exemplary ear muff attachment assembly 100 having an arm 120 in a
first position, intermediate position, and second position,
respectively. Arm 120 is rotatable about a first axis of rotation
10 between a first position (FIG. 3a) and an intermediate position
(FIG. 3b), and about a second axis of rotation 20 between the
intermediate position (FIG. 3b) and the second position (FIG. 3c).
Rotation of arm 120 switches or flips from the first axis of
rotation 10 to the second axis of rotation 20 at the intermediate
position.
In an exemplary embodiment, first axis of rotation 10 is defined by
a first lever seat 115 of housing 110. First lever seat 115 has a
first depression or recess 116 configured to accommodate a
complementary shaped arm protrusion 124 of arm 120. Arm protrusion
124 is able to rotate or pivot within first recess 116 about first
axis 10 passing through arm protrusion 124 as arm 120 moves between
first and intermediate positions. Second axis of rotation 20 is
defined by a second lever seat 125 of arm 120. Second lever seat
125 has a second depression or recess 126 configured to accommodate
a complementary shaped housing protrusion 114. Second depression or
recess 126 is able to rotate or pivot over housing protrusion 114
about second axis 20 passing through housing protrusion 114 as arm
120 moves between the intermediate and second positions.
In various alternative exemplary embodiments, arm 120 may include
first lever seat and housing 110 may include second lever seat, or
arm 120 or housing 110 may include both of the first and second
lever seats defining first and second axes of rotation 10, 20.
First and second axes of rotation may be defined by other suitable
shapes and/or features as known in the art.
FIG. 3a shows arm 120 of ear muff attachment assembly 100 in a
first position in which ear muff 130 (not shown) is in an active
position. Spring 150 exerts a spring force (Fs) at first end region
121 of arm 120 resulting in a force (F) at second end region 122 of
arm 120 and ear muff 130 that causes ear muff 130 to press against
the head and/or ear of a user. Force (F) acts to maintain ear muff
130 in the active position while providing an appropriate seal
between ear muff 130 and the user's head and/or ear. A user may
move ear muffs 130 away from their ear and out of the active
position by overcoming force (F) and rotating or pivoting arm 120
past the intermediate position, for example.
FIG. 3b, shows arm 120 in an exemplary intermediate position in
which first axis of rotation 10, and first and second spring
engagement locations 151, 152, where spring 150 engages housing 110
and arm 120, respectively, are substantially aligned. In this
intermediate position, spring 150 exhibits a maximum compression
and exerts a maximum spring force (Fs). Spring force (Fs) acts in a
direction extending though first and second axes of rotation 10,
20. Accordingly, the force (F) exerted at second end region of arm
120 and/or ear muff 130 is substantially zero. That is, at the
intermediate position shown in FIG. 3b, spring force (Fs) does not
result in a force acting to rotate arm 120. Movement of arm 120
away from the intermediate position results in a force (F) towards
the first or second positions. For example, movement beyond the
intermediate position away from the first position causes the
direction of spring force (Fs) on arm 120 to flip or switch from
being generally directed outwardly from housing 110 to being
generally directed towards housing 110. Force (F) similarly flips
or switches such that force (F) acts to move arm 120 and ear muffs
130 towards a second position, and rotation of arm 120 switches
from rotation about first axis of rotation 10 to rotation about
second axis of rotation 20.
FIG. 3c shows arm 120 in an exemplary second position in which ear
muff 130 is in a standby position and ear muff 130 is raised and
positioned away from and/or out of contact with a user's head.
Spring 150 exerts a spring force (Fs) at first end region 121 of
arm 122 that causes ear muff 130 to resist movement away from the
standby position. First end region 121, or other portion of arm
120, is pushed against a stop 118 or other surface of housing 110
to prevent further rotation of arm 120 beyond the standby position.
Accordingly, when resting in the standby position, force (F) is
zero. A user may move ear muff 130 towards their ear and into an
active position by moving ear muff 130 out of the standby position,
overcoming force (F) acting to return arm 120 to the standby
position, and rotating or pivoting arm 120 past the intermediate
position, for example. When arm 120 passes the intermediate
position, the direction of force (F) flips or switches and ear muff
130 is pushed into the active position.
Force (F) exerted at a second end region 122 of arm 120 and ear
muff 130 is related to a position of arm 120 and compression or
activation of spring 150. In an exemplary embodiment, force (F) may
be described as acting in a direction parallel to the motion of
second end region 122 of arm 120 and orthogonal to the axis of
rotation. In embodiments in which arm 120 has a "Y" or branched
configuration, force (F) may include a component acting at each
attachment location, for example, such that force (F) is a total
force acting on ear muff 130.
In the exemplary embodiment of FIGS. 3a through 3c, an approximate
force (F) may be calculated based on a spring force (Fs), effective
length (A) between the axis of rotation and location of force (F),
length (B) between the arm axis of rotation and second spring
engagement location 152, initial length (Li) of spring 150,
compressed length (Ls) of spring 150, length (D) between the axis
of rotation of arm 120 and first spring engagement location 151,
angle (.alpha.) formed between (D) and (B), and lengths (C), (H1),
and (H2), using the following relationships: F=(Fs)*(H2)/(H1)
Fs=(Li-Ls)*K H1=cos(.alpha.)*A H2=sin(arccos(C/Ls)*D)
C=D-[cos(.alpha.)*B]
Lengths (H1), (H2), (Ls), and (C) vary as arm 120 moves between the
first position and an intermediate position, and spring force (Fs)
and force (F) similarly vary as arm 120 rotates and pivots. Lengths
(A), (B), and (D) remain constant while arm travels between the
first position and the second position. When arm 120 moves past the
intermediate position, arm 120 switches or flips from rotation
about first axis 10 to rotation about second axis 20 and lengths
(A), (B), and (D) simultaneously change. In this way, force (F)
also varies depending on whether arm 120 is between the first
position and intermediate position or between the intermediate
position and the second position, even for respective positions in
which spring spring force (Fs) is equal. Accordingly, ear muff
attachment assembly 100 allows a force (F) required to move ear
muff 130 from the first position to the intermediate to be greater
than the force (F) required to move ear muff 130 from the second
position to the intermediate position. An ear muff attachment
assembly having two axes of rotation and resulting in a lower force
required to move ear muff from a second or standby position also
allows for a greater flexibility in the distance traveled between
the first and second positions. For example, because force (F)
between the intermediate position and second position is lower, an
ear muff may be positioned a greater distance from a user's head in
the standby position, if desired.
In various exemplary embodiments, length (B) may be between about 3
mm and 25 mm, 8 mm and 17 mm, or about 11.5 mm, length (D) may be
between about 10 mm and 30 mm, 15 mm and 25 mm, or about 22 mm, and
ear muff attachment assembly may be configured such that angle (a)
may be between 5.degree. and 35.degree., 15.degree. and 30.degree.,
or about 25.degree. in the active and/or standby position. An ear
muff attachment device having such values allows a configuration
resulting in a desired force (F), spring force (Fs), and range of
motion of arm 120 as described herein.
An ear muff attachment assembly having such geometry produces a
maximum force between the first and intermediate positions (Fmax1)
and a maximum force between second and intermediate positions
(Fmax2). Maximum force (Fmax1) between first and intermediate
positions represents a maximum force a user must exert to move ear
muff 130 from a first, active position to a second, standby
position, and maximum force (Fmax2) between second and intermediate
positions represents a maximum force a user must exert to move ear
muff 130 from a second, standby position to a first, active
position. Ear muff attachment assembly 100 may be configured to
have a desired variation between (Fmax1) and (Fmax2). In various
exemplary embodiments, (Fmax2) is between 25% and 85% of (Fmax1),
between 45 and 85% of (Fmax1), or about 75% of (Fmax1). In one
exemplary embodiment, ear muff attachment assembly 100 has an
initial spring length (Li) of 12.8 mm and spring constant (K) of
200 N/mm. When arm 120 is between a first position and an
intermediate position, and rotates about first axis 10, ear muff
attachment assembly 100 has lengths (A1) of 100 mm, (B1) of 11.5
mm, and (D1) of 22 mm. When arm 120 is between a second position
and an intermediate position, and rotates about second axis 20, ear
muff attachment assembly 100 has lengths (A2) of 103.8 mm, (B2) of
7.7 mm, and (D2) of 18.2. An ear muff attachment assembly having
such geometry produces a maximum force (Fmax1) between the first
and intermediate positions of approximately 18.1 N and a maximum
force (Fmax2) between second and intermediate positions of 13.3
N.
An ear muff attachment assembly as described herein provides
several features and advantages over prior devices. An ear muff
attachment assembly having two axes of rotation facilitates an
assembly that allows an ear muff to be moved into an active
position with much less force than required to move the ear muff
into a standby position. The force required to move the ear muff
may be calibrated such that a maximum force a user must exert to
move the ear muff from an active position to a standby position is
less than, or exhibits a preferred value, as compared to a maximum
force a user must exert to move the ear muff from a standby
position to an active position. A user is able to readily and
comfortably rotate or pivot arm 120 and spring force (Fs). Further,
an exemplary ear muff attachment assembly may be configured such
that an arm has a greater range of motion while exhibiting a
desired force (F), and an ear muff may reside in a standby position
that is a greater distance from a user's head. Additionally, an ear
muff attachment assembly having two axes of rotation allows the
above advantages to be achieved while minimizing a force exerted by
a spring component when the arm and earmuff are in a standby
position. Such a configuration reduces stress on a housing and/or
other components of the ear muff attachment assembly and provides a
durable and robust assembly.
The present disclosure has now been described with reference to
several embodiments thereof. The foregoing detailed description and
examples have been given for clarity of understanding only. No
unnecessary limitations are to be understood therefrom. It will be
apparent to those skilled in the art that many changes can be made
in the embodiments described without departing from the scope of
the invention. Thus, the scope of the present invention should not
be limited to the exact details and structures described herein,
but rather by the structures described by the language of the
claims, and the equivalents of those structures. Any feature or
characteristic described with respect to any of the above
embodiments can be incorporated individually or in combination with
any other feature or characteristic, and are presented in the above
order and combinations for clarity only. That is, the present
description contemplates all possible combinations and arrangements
of various features of each of the exemplary embodiments and
components describe herein, and each component may be combined or
used in conjunction with any other component as desired for a
particular application.
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